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Sep 14, 2023

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Australian scientists have made an important discovery that could explain why

Australian scientists have made an important discovery that could explain why some people get sicker than others when they get a virus like Covid – and it is all down to the success of immune* cells armed with a so-called "licence to kill".

The Victorian team's discovery may now lead to new therapies to help fight other viruses and even cancer.

The key breakthrough by researchers from the Doherty Institute in Melbourne and German colleagues at the University of Bonn and the Charité University Hospital in Berlin, found that "licensing" CD8+ T cells to destroy an infection happens with different viruses, including Covid-19.

The team found that if permitted, antiviral* T cells go out to seek and destroy viruses as part of the body's emergency response to infection.

But University of Melbourne senior researcher Professor Sammy Bedoui said these cells need controlled permission or else they can go rogue* and destroy more than the virus.

How are cells given permission to act?

This permission is given by molecules* including Type 1 interferons – signalling proteins* that tell your immune system that viral cells are in your body – and T cells, the helper cells. Interferons are so named because they "interfere" with a virus trying to invade a cell and are naturally produced to help the body's immune system fight infection.

Tug of war

The team found that Covid and other viruses continuously try to "outsmart" the immune system and often do so by reducing or delaying the production of Type I interferons.

Professor Bedoui said how sick a patient becomes from an infection often reflects this tug of war* between the immune response and the virus trying to invade it.

A laboratory head at the Doherty Institute, Professor Bedoui said CD8+ T cells are born with the ability to attack and destroy virus-infected cells, but to do their job, they need other cells and molecules, such as the Type 1 interferons, to send appropriate combinations of signals to unleash* their fightback capacity.

"They have to be tapped on the shoulder and told ‘now you can kill the infected cells’," Professor Bedoui said.

Regulated response

This "licence to kill", he said, needs to be carefully regulated. Too strong a response by the T cells can actually make the patient sicker.

Professor Bedoui said such overshooting* reactions are called "immunopathology*" and they are thought to be an important feature in patients who develop severe Covid-19. However, many aspects of why this happens remain unclear.

"Some patients develop antibodies that block the interferon and these are the patients who died from Covid," he said.

"We used that to understand the role of those interferons in Covid and found the virus acts against interferons and blocked the response."

That is where CD8+ T cells depend on helper cells.

"These helper cells can actually make the body work with less interferons so there is greater flexibility," Professor Bedoui said.

"The virus can try to block the interferon, but as long as helper cells are around, they provide an extra layer of defence."

The discovery is a new piece in the puzzle and makes a lot of sense, he said.

"Our research not only provides a better understanding of why some people get very sick upon (Covid) infection, but importantly has identified a number of new potential therapeutic targets that can be exploited* for better management of respiratory* viruses in the future," Professor Bedoui said.

The study was published last week in Nature Immunology*.

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QUICK QUIZ

LISTEN TO THIS STORY

CLASSROOM ACTIVITIES1. Immune cells flow chartCreate a flow chart (a diagram that shows how a system or process works) on what the immune cells in the body do to help fight off an infection.

Use the facts from the Kids News article as the basis of your flowchart.

Use only key words within a diagram to describe what happens from when an infection forms to how the body fights it, according to this new research.

Your flow chart should be as simple and as easy to read as possible to explain the process.

Time: allow 30 minutes to complete this activityCurriculum Links: English; Science; Critical and Creative Thinking

2. Extension How do you think this new research could help scientists and immunologists make more targeted therapies to attack viruses such as Covid?

How might it help researchers cure diseases such as cancer?

What would you name the "helper" cells discussed in the article?

Time: allow 15 minutes to complete this activityCurriculum Links: English; Science; Critical and Creative Thinking

VCOP ACTIVITY Mayday! Mayday!Write a creative piece about a viral invasion happening in someone's body.

Use key facts from the article to create your characters – the different cells and the virus cells. Write the piece as if it were a war or invasion in the real world, but make the people in the war the body's cells verses the virus cells.

Remember the article tells us about some of the different roles the body's cell play as well as what the virus cells do, so use this information in your story as part of the plot.

Challenge: Make your story suitable for younger students to explain to them how virus work. Then use it to promote some ways they can try and stay well and keep the virus’ away by staying warm, clean and not sharing germs.

Re-read your story to a peer to see what they think. Ask for some feedback on anything you can do to improve it.

Turn it into a book for a younger grade level.